In cellular systems, a terminal device such as User Equipment (UE) is allowed to initially request a connection setup with a network device such as an enhanced NodeB (eNodeB). Such a procedure is commonly referred to as “Random Access”.
In Long Term Evolution (LTE), the random access procedure has in two forms, allowing access to be either contention-based or contention-free. In the contention-based random access procedure, UE needs to transmit a random access preamble to its serving eNodeB on the Physical Random Access Channel (PRACH) in the first step (Message 1). Upon reception in the eNodeB, the preamble should thus be detected with high accuracy, such that the eNodeB may perform the following step in the contention-based random access procedure.
The emerging 5G technologies are characterized with many new features, such as much higher carrier frequencies and an increased number of antenna elements. As such, some new demands have to be considered while designing random access preambles for the 5G communication system, for example, reducing phase noise and frequency error for the higher carrier frequency and reducing the hardware complexity with multiple antennas.